The present invention relates to a firing device for restraint means in a vehicle, at least one firing element, surrounded by a conductive capsule, and circuit meansxe2x80x94preferably for the energy supply, for triggering and/or diagnosis of the firing elementxe2x80x94being accommodated in a common module housing, and the module housing being provided with terminal posts which, one the one side, are contacted to the circuit means, and on the other side, are brought out from the module housing for connection to a plug connector.
A firing device is described in German Patent No. 196 10 799. This known firing device is conceived such that it has the smallest possible outer dimensions compared to firing devices used till now, so that, for example, it can even be accommodated in the steering wheel of a vehicle. Namely, heretofore the firing element and an ignition power module, which contained circuitry for energy supply, for triggering and/or diagnosis of the firing element, were accommodated in separate modules contactable to each other via connectors. According to German Patent No. 196 10 799, besides a firing element generating the thermal energy for igniting an ignition mixture, also arranged in a module housing are circuit elements, for instance, for the energy supply, the triggering and/or diagnosis of the firing element. Located in the module housing, below the firing element, is a rectangular-shaped member in which contact pins for the firing element are integrated, and on whose sidewalls circuit elements are applied. The rectangular-shaped member is used both for fixing contact pins for the firing element in place, as well as for positioning terminal posts which are brought out from the module housing for contacting to a plug connector.
When handling the firing device prior to or during installation in a motor vehicle, an electrostatic charging can occur within the module housing, which means a disruptive discharge voltage can develop that is sufficient to trigger the firing element. In the same way, electrostatic chargings in the firing device are possible when it is already installed in a vehicle. Therefore, an object of the present invention is to provide a firing device which prevents an unintentional triggering of the firing element as a result of electrostatic charging.
According to the present invention, present in the module housing is at least one conductive member, contacted to the firing capsule, which has a defined distance to the individual terminal posts, such that in response to an electrostatic charging, a voltage sparkover occurs between the terminal posts and the conductive member. The terminal posts, together with the conductive member, form a spark gap over the defined distance, via which a discharge occurs when the charge exceeds a certain value. The charge is thereby prevented from discharging directly to the firing element, and there causing an unintentional triggering.
Accordingly, the conductive member is mounted on a base that fixes the terminal posts in position. The conductive member can be contacted to the firing capsule either by the conductive member having a cut-out for mounting the firing capsule, or by providing the firing capsule with a sleeve which is able to be placed over the conductive member. In this context, the conductive member can be a metal ring that rests on the substrate and has a collar forming an angle, over which the sleeve of the firing capsule can be placed.
Circuit means can be arranged on a substrate, a spring element resting on the substrate producing an electrical connection between the circuit means on the substrate and contact pins of the firing element.